Journal article

Publication year: 2005

Pages: 1129-1136

Journal: Biological Chemistry

Volume number: 386

Issue number: 11

ISSN: 1431-6730

eISSN: 1437-4315

DOI Link: https://doi.org/10.1515/BC.2005.129

Publisher: De Gruyter Brill

Abstract: 
Thioredoxin peroxidase 1 (TPx1) of the malarial parasite Plasmodium falciparum is a 2-Cys peroxiredoxin involved in the detoxification of reactive oxygen species and - as shown here - of reactive nitrogen species. As novel electron acceptor of reduced TPx1, we characterised peroxynitrite; the rate constant for ONOO- reduction by the enzyme (1 x 10(6) m(-1) s(-1) at pH 7.4 and 37 degrees C) was determined by stopped-flow measurements. As reducing substrate of TPx1, we identified - aside from thioredoxin plasmoredoxin; this 22-kDa protein occurs only in malarial parasites. When studying the potential roles of Cys74 and Cys170 of Tpx1 in catalysis, as well as in oligomerisation behaviour, we found that replacement of Cys74 by Ala influenced neither the dimerisation nor enzymatic activity of TPx1. In the C170A mutant, however, the k(cat)/ K-m for reduced Trx as a substrate was shown to be approximately 50-fold lower and, in contrast to the wildtype enzyme, covalently linked dimers were not formed. For the catalytic cycle of TPx1, we conclude that oxidation of the peroxidatic Cys50 by the oxidising substrate is followed by the formation of an intermolecular disulfide bond between Cys50 and Cys170' of the second subunit, which is then attacked by an external electron donor such as thioredoxin or plasmoredoxin.

Harvard Citation style: Nickel, C., Trujillo, M., Rahlfs, S., Deponte, M., Radi, R. and Becker, K. (2005) Plasmodium falciparum 2-Cys peroxiredoxin reacts with plasmoredoxin and peroxynitrite, Biological Chemistry, 386(11), pp. 1129-1136. https://doi.org/10.1515/BC.2005.129

APA Citation style: Nickel, C., Trujillo, M., Rahlfs, S., Deponte, M., Radi, R., & Becker, K. (2005). Plasmodium falciparum 2-Cys peroxiredoxin reacts with plasmoredoxin and peroxynitrite. Biological Chemistry. 386(11), 1129-1136. https://doi.org/10.1515/BC.2005.129